There are known pneumatic tools for normal pressure using an operating air pressure in a normal pressure region equal to or lower than, for example, 8 kg/cm2 and for high pressure used in a pressure region at high pressure having a high operating pressure region and according to the tools. In these tools, there are used plugs attached to hoses for supplying compressed air to the tools respectively having exclusive shapes for preventing erroneous connection. Further, according to a compressor capable of supplying compressed air to either of the tools for high pressure and for normal pressure, the compressor needs to be installed with at least respective ones of an air output port exclusive for high pressure and an air output port exclusive for normal pressure, and the respective compressed air output ports need to be mounted with exclusive couplers and pressure regulators for connecting plugs exclusive for high pressure and normal pressure. This constitutes a factor of increasing cost of the compressor.
Hence, as a related art, the applicant has already proposed a compressed air output apparatus installed with a coupler connectable to both of a plug exclusive for high pressure on a side of a high pressure tool and a plug exclusive for normal pressure, in which in the case the coupler is connected with the plug for normal pressure, when a supplied pressure regulated by a pressure regular exceeds an operating pressure region of a normal pressure tool, supply of compressed air to a side of the normal pressure plug is cut off. By this constitution, a single compressor output port may be installed in using either of the tools for normal pressure and high pressure and therefore, the cost of the compressor can be reduced.
As shown by FIG. 15, according to the constitution of the coupler in the compressed air output apparatus which has already been proposed as the related art, the coupler is formed with a socket portion 51 connectable to either of the respective exclusive plugs for high pressure and for normal pressure at one end thereof and is formed with a cutoff valve 52 for preventing compressed air supplied from other end side from leaking in a state in which the socket portion 51 is not connected with the plug. Compressed air is communicated with a side of the plug by separating a movable valve body 53 constituting the cutoff valve 52 from a valve seat 54 by mounting the plug.
As shown by FIG. 16 and FIG. 17, there is provided an opening/closing valve 55 for closing supplied air from flowing to the socket portion 51 when a supplied pressure from a pressure regulator becomes high by exceeding the operating pressure region of the normal pressure tool in a state of being connected with a plug P1 for normal pressure. The opening/closing valve 55 is constituted to operate by a pressure receiving face 55a for operating the opening/closing valve 55 in a closing direction by receiving the air pressure supplied from the pressure regulator and a spring 56 for urging the opening/closing valve 55 in an opening direction opposedly to the pressure receiving face 55a, and the opening/closing valve 55 cuts off an air path by fitting an O ring 57 of the movable valve body 53 into a cylindrical portion 55b of the opening/closing valve 55 in cooperation with the movable valve body 53 moved by mounting the normal pressure plug P1. The opening/closing valve 55 is set with a spring force of the spring 56 and an area of the pressure receiving face 55a for receiving compressed air such that the opening/closing valve 55 is operated in a closing direction at an upper limit of the operating air pressure region, and operated when a regulated pressure of the pressure regulator exceeds the above-described set pressure to cut off supply of compressed air to the normal pressure plug P1 to thereby present compressed air at the pressure exceeding the operating air pressure region from being supplied to the tool exclusive for normal pressure.
However, in a state of being connected with the tool exclusive for normal pressure, when the supplied air pressure exceeds the operating air pressure at normal pressure by operating to regulate the pressure regulator for setting the pressure used for the tool, naturally, the opening/closing valve 55 is operated to cut off flow of compressed air, however, in a state of temporarily closing the opening/closing valve 55, the cylindrical portion 55b of the opening/closing valve 55 is fitted to the O ring 57 of the movable valve body and therefore, a sliding resistance is increased, further, the opening/closing valve 55 of the above-described mechanism is constituted to be operated by a difference between the pressure receiving face 56a of a face on an upstream side and a pressure receiving face 56c of a face on a downstream side and the spring force, in a state in which the path is cut off by operating the opening/closing valve 55, the two pressure receiving faces are cut off by the opening/closing valve body, there is a case in which the pressurized receiving face side 55c on the downstream side facing the side of the plug is reduced in pressure to almost 0 kg/cm2, the pressure difference operating to the two pressure receiving faces is increased and therefore, there is brought about a state in which the opening/closing valve 55 is not operated in the direction of opening the air path even when the supplied air pressured is reduced from the above-described set pressure by a small amount by regulating the pressure regulator again. For example, when the opening/closing valve 55 is set to operate in the closing direction by the supplied air pressure of 8 kg/cm2, in the case of the temporarily closed opening/closing valve 55, the opening/closing valve 55 cannot be operated unless the supply pressure of the pressure regulator is reduced down to 5 kg/cm2. Therefore, there poses a problem that when the tool for normal pressure is used, the tool is not user-friendly.
Further, according to the above-described mechanism, in a state in which neither of the plugs for high pressure and normal pressure is mounted thereto, the movable valve body 53 and the opening/closing valve 55 are brought into a state of being separated from each other and as shown by FIG. 18, in a procedure of mounting the normal pressure plug P1 to the socket portion 51, there is brought about a state in which the cutoff valve 52 is opened and the opening/closing valve 55 is not fitted to the movable valve body 53. Under the state, when the regulated pressure of the pressure regulator is regulated to high pressure and air at high pressure is supplied to the supply port of the coupler, during a time period until compressed air is cut off by cooperating the opening/closing valve 55 and movable main body 53 in a procedure of connecting the normal pressure plug P1, it is brought about that compressed air at high pressure is supplied to the normal pressure plug P1 and compressed air at high pressure is supplied to the tool exclusive for normal pressure. Further, when the regulated pressure of the pressure regulator is changed to high pressure in using the tool exclusive for normal pressure, the opening/closing valve 55 is operated and supply of compressed air at high pressure to the side of the plug is cut off, however, also when the normal pressure plug P1 mounted to the socket portion 51 is detached from the state, similar to the above-described, there is a case in which the opening/closing valve 55 is opened by being separated from the movable valve body 53 before closing the cutoff valve 52 and compressed air at high pressure is supplied to the tool exclusive for normal pressure.
It is a first object of the invention to resolve the above-described problem of the related art and enabling to prevent supply of compressed air exceeding an operating air pressure of a normal pressure tool to the normal pressure tool by cutting a flow path when an output air pressure at a pressure regular exceeds a set pressure in connecting a normal pressure plug and swiftly supplying compressed air at an operating air pressure by regulating again a supply pressure at the pressure regulator to be equal to or lower than the operating air pressure after cutting off the flow path.
Further, when compressed air exceeding an operating pressure region of a normal pressure tool is supplied in connecting or separating a pneumatic tool exclusive for normal pressure, not only service life of the tool is significantly deteriorated but also a danger is accompanied thereby depending cases. It is a second object of the invention to provide a compressed air output apparatus in which the above-described problem of the related art is resolved and high pressure air is not supplied to a tool exclusive for normal pressure via a normal pressure plug even in the midst of operating to attach or detach a normal pressure plug in a state in which compressed air at high pressure is supplied to a coupler.